very close to the threshold of excellence in sound reproduction


Model LL2.1 is the next generation of the original LL2 which was the first in the line of LAMM vacuum tube preamplifiers. Unique topology and application of the most advanced technological resources and processes bring the LL2.1 very close to the threshold of excellence in sound reproduction. A main distinction of the LL2.1 from any other comparable type of preamplifiers is its almost inaudible sonic signature. When connected to an appropriate type of power amplifiers, especially LAMM amplifiers, it assures the recreation of a three-dimensional soundstage without boundaries and limitations.

design elements


The LL2.1 features a topology that brings out the most natural sound performance in the audio path, as well as graceful and sophisticated design. It employs a pure class A operation from input to output; all stages are single-ended. The preamplifier’s audibly neutral power supply features a full-wave vacuum rectifier. This rectifier, together with a choke-containing filter, allows to practically get rid of the hum and buzz and, in the end, to ensure the verity of dynamic range without coloration.

Other features include 3 inputs; 1 tape loop; 2 sets of outputs; front panel muting switch; attenuator for gain reduction by 15 dB; built-in remote on/off for LAMM power amplifiers; protection circuitry coupled with automatic mute at turn on/off.

components


Each preamplifier is carefully hand-crafted with matched components of the highest quality, some of which include military graded low noise DALE metal film resistors; NOBLE potentiometers; ELECTROCUBE and ROEDERSTEIN film capacitors; high frequency switching grade CORNELL DUBILIER electrolytic capacitors; and specially selected long life vacuum tubes. The LL2.1 features a custom-designed power transformer.

The LL2.1 is available in two versions: standard and deluxe, both of which utilize identical chassis, PC-board and parts.
In deluxe version, the power supply energy storage is approximately twice that of the standard version (four identical light-blue capacitors next the choke; only two of these are installed in regular version — see first detail image insert).
Also, in deluxe version, all film capacitors in critical paths are paralleled by polystyrene capacitors of the highest available quality (yellow capacitors on two images — right and below).

Gallery


audio critic reviews (coming soon)


Measurement


The following data represents the LL2.1 as performed by an independent party:
Mr. Bascom H. King of BHK Laboratory (bhk@rain.org).

Rated Output Voltage
From 20Hz-20KHz into 41-KOhm load: 1 Volt RMS
Voltage Gain
7.87 ± 2% or 17.92 ± 0.2dB.
Attenuation
5.62 ± 10% or 15 ± 0.85dB.
Absolute Phase
Inverting
Frequency Response
From 1-30 Volts RMS: (-0dB) 20 Hz – 20 KHz. (-3dB) 1.55 Hz -400 KHz.
Slew Rate
Vout=28.8 Volts peak-to-peak of square-wave signal, F=10KHz: 41 Volts per microsecond.
Rise Time
Vout=28.8 Volts peak-to-peak of square-wave signal, F=10KHz: 1 microsecond.
Total Harmonic Distortion from 20 Hz – 20 KHz
Vout=2 Volt RMS: no more than 0.03%
Vout=30 Volts RMS: no more than 1%
IM Distortion (60Hz:7KHz 4:1) SMPTE):
Vout=2 Volt RMS: no more than 0.03%
Vout=30 Volts RMS into IHF load: no more than 1%
Inputs
Single-ended gold plated single-ended RCA connectors.
Input Sensitivity
Vout = 1 Volt RMS: 0.127 Volts RMS ± 2%.
Input Impedance
50 KOhms ± 10%.
Outputs
Single-ended gold plated single-ended RCA connectors.
Corrected Output Impedance
Typically 250 Ohms.
Noise
Signal-to-noise ratio, below 2 Volts RMS output, unweighted: better than 84 dB.
Signal-to-noise ratio, below 2 Volts RMS output, A-weighted: better than 94 dB.
Operating Temperature
Operating Temperature: -4 to +104 degrees Fahrenheit (-20 to +40 degrees Celsius) ambient.
Power Supply
Nominal line voltage: 100-240 Volts 50/60Hz. Input voltage range: ±10%.
One power transformer, one filter choke, one full-wave vacuum rectifier, one solid-state analog non-switching voltage regulator.
AC voltage intensively filtered by special RFI power line filter.
Front Panel Controls
POWER switch.
REMOTE switch.
MUTING switch.
LEFT GAIN control.
RIGHT GAIN control.
ATTENUATOR (-15 dB) switch.
SELECTOR switches.
MONITOR switch.
LED control.
Rear Panel Connectors & Controls
IEC 320 POWER INLET (3 lug).
EARTHING POST (gold plated).
REMOTE CONTROL plug.
Four pairs of INPUT CONNECTORS RCA for Line and Tape inputs.
Three pairs of OUTPUT CONNECTORS RCA for Tape, Output 1, and Output 2.
Features
Pure class A vacuum tube design. All stages are single-ended.
High-current drive capability, in combination with unique single-ended class A circuitry, guarantee the preamplifier to drive any cable and any reasonable real world load, while maintaining its practically inaudible sonic signature.
This design is unique to LAMM INDUSTRIES, INC.
AC voltage selector: 100/120/220/230/240 Volts, internally switchable.
Safety:
Unique electronic protection circuit enables muting of the outputs until the preamplifier is stabilized after a turn-on, as well as functioning of the preamplifier in a “muting” mode during operation, and automatic switching to muting in case the AC line drops or is interrupted.
AC voltage fuses: 1 Amp slo-blo for 100/120 Volts, 0.5 Amp slo-blo for 220/230/240 Volts.
General
Power Consumption: Typically 40 Watts.
 Burn-in Time at Factory: Minimum 72 hours.
Recommended Burn-in Time in End-user’s System: Minimum 50 hours.
Warm-up time: Minimum 45 minutes.
Unit dimensions: 4.5 inches high x 19 inches wide x 13.875 deep + 1.375 inches for front handles.
Crate dimensions: 23″ x 19″ x 10″ (58.42cm x 48.26cm x 25.4cm).
Unit weight: 20 Lbs (9.1 Kg).
Shipping weight: 36 Lbs (16.3 Kg).
Tube Complement left channel:
V101 – 12AU7A (first amplification stage), V103 – 6DJ8 (second amplification stage).
Tube Complement right channel:
V101 – 12AU7A (first amplification stage), V103 – 6DJ8 (second amplification stage).
Tube Complement:
V105 – 6X4/6202 (full wave voltage rectifier).